Switches frequently have a background illumination, which makes it possible to find and actuate the switch in a hallway or on a device, for example, on a household appliance, even in darkness or inadequate illumination conditions. In addition, a corresponding illumination can also indicate the status of the switch, such as the on/off state.
In general, LEDs (LED=light-emitting diode) or ACPEL arrangements are used as light sources for the background illumination of switches; further common designations for ACPEL arrangements are: electroluminescence elements, electroluminescence arrangements, or electroluminescence devices, wherein electroluminescence is typically abbreviated with EL.
The combination of switch and background illumination is often constructed from at least two separate units, for example, from a mechanical switch and corresponding LEDs or a mechanical switch and ACPEL arrangements.
These combinations known from the prior art of illuminated switches made of separate elements have the disadvantage that their provision is costly and subject to failure because of the use of mechanical parts. In addition, further disadvantages arise, such as higher weight, restricted shape freedom and therefore restricted design freedom, and a large installation depth.
In addition, layer structures are known from the prior art, in which non-mechanical switches are backlit using LEDs or ACPEL arrangements.
Thus, WO2008/131305A1 discloses a printed capacitive switch, which is backlit by LEDs. US2005/0206623A1 discloses a capacitive switch, which is backlit by an ACPEL arrangement. US2008/202912A1 discloses a capacitive switch, which is backlit by LEDs or OLEDs (OLED=organic light-emitting diode).
ACPEL arrangements are frequently obtainable by way of a printing method.
These combinations of illuminated switches have the advantage in relation to illuminated switches made of separate elements that they do not have any mechanical parts and are therefore less susceptible to failure, and they have a lower weight. In addition, these combinations form uninterrupted surfaces at least on the side facing the user. Such surfaces are easier to keep clean, on the one hand, and they provide a higher-quality aesthetic impression, on the other hand.
The combinations of illuminated switches disclosed in the above-mentioned intellectual property have the disadvantage that they only provide flat or slightly curved planar parts, or the switch is deformed three-dimensionally, as in the case of WO2008/131305A1, while the backlighting is provided by LEDs. Since these LEDs cannot be shaped, the background illumination of the deformed switch is not free of shadows, nor uniform.
It has been known since WO03/037039A1 that ACPEL arrangements can be deformed three-dimensionally nearly arbitrarily. However, these arrangements have heretofore only been used for the purpose of backlighting three-dimensionally deformed displays, without shadows and uniformly. These displays have no further electrotechnical components in the deformed region except for the ACPEL arrangement, however.
Backlighting three-dimensionally deformed electrotechnical components, for example, a switch, using a similarly three-dimensionally deformed ACPEL arrangement is not known from the prior art.
Attempts to build such switches have heretofore failed because delamination of the layer structure occurred during the shaping as a result of the drawing and compression of the various layers, which delamination damaged the entire part and therefore also its functional capability.
In addition, interference of the ACPEL operating voltage with the switching signal of the switch occurred in the switches known from the prior art. The switching signal of the switches was interfered with by the AC voltage, using which the ACPEL arrangement is operated, in such a manner that detection of a switching procedure was made more difficult or impossible.